The applications of backlight structures are common in everyday life such as digital cameras, digital Walkman's, cellular phones, televisions, and computers. Taking computers for example, the mainstream of modern computer displays is liquid crystal displays. Any trail of traditional cathode ray tube displays is hardly seen. Owing to the trend, lightness, thinness, shortness, smallness, as well as high performance have become concepts of the invention of technical products. A notebook computer is an invented product based on the concepts. The majority of the displays of notebook computers adopt backlight structures as their light sources. In order to conform to the invention concepts of lightness, thinness, shortness, smallness, and high performance, backlight structures with a V-cut light-entering side have gradually become the main stream. The framework thereof can adopt fewer optical thin films to concentrate light energies on the normal viewing angle such that the purposes of lightness, thinness, as well as high luminance can be achieved.
Please refer to FIGS. 1 and 2 altogether, which are a structural schematic diagram and a cross-section view of a backlight structure according to the prior art. As shown in the figures, the backlight structure with a V-cut light-entering side according to the prior art comprises a light-guide plate 10, a reflector plate 20, a lamp 30, and a lampshade 40. The reflector plate 20 is adapted beneath the light-guide plat 10, and the lamp 30 is adapted on one side of the light-guide plate 10. The lamp 30 is a cold cathode fluorescent lamp. A plurality of insulating sleeves 36 covers both sides of the lamp 30, and the plurality insulating sleeves 36 is made to shield electrodes 335 on both sides, respectively. In addition, the lampshade 40 is adapted on one aide of the light-guide plate 10 and covers the lamp 30.
By means of the insulating sleeves 36, the electrodes 335 on both sides of the lamp 30 are protected so that the short-circuit problem of the lamp 30 can prevented. Furthermore, In the process of assembling the backlight structure, both sides of the lamp 30 are soldered with high- and low-voltage wires first. Then the insulating sleeves 36 are slip on, and surround the lamp 30. Afterwards, the lamp 30 and the lampshade 40 are assembled. When the lamp 30 and the lampshade 40 are assembled, the inner sides of the insulating sleeves 36 on both sides of the lamp 30 will overlap with the lampshade 40, and will plug the insulating sleeves 36 into the opening of the lampshade 40. The insulating sleeves 36 will be fixed temporarily inside the opening of the lampshade 40 for later use in the assembly procedure.
Nevertheless, most of the insulating sleeves 36 are made of plastic, compressive, and flameproof rubber materials. If the materials are opaque, the propagation of light will be shaded to some degree. Notebook computers adopt the backlight structure with a V-cut as their light source to meet the requirement of designing with lightness, thinness, shortness, and smallness. However, because of the backlight structure with a V-cut, light is difficult to propagate parallel to the direction of the lamp 30 in the light-guide plate 10. As a result, the luminance at bottom-left and bottom-right corners is relatively low, which in turn makes the bottom-left and bottom-right corners of the display appear darker.
Another method is thereby adopted. In which method, the lampshade 40 that is a transparent is used to make part of light pass through it and illuminate to the bottom-left and bottom-right corners of the light-guide plate 10. Nonetheless, in the regard of the backlight structure, the temperature on the lampshade 40 after the illumination of the lamp 30 is quite high. If the transparent lampshade 40 is used, then the transparent material of the transparent lampshade 40 will face the problem of being unable to endure high temperatures. That is to say, the problem of bad flameproof characteristics will occur. Moreover, the transparent material will cause the concern of yellowing after using it in a high-temperature environment for a period of time.
Accordingly, another method is used. Burnish using special cutting tools is applied on the light-entering surface of the light-guide plate 10, that is, the side on which the light-guide plate 10 and the lamp 30 adjoin, so that more light can propagate towards the bottom-left and the bottom-right corners of the light-guide plate 10. Alternatively, a surface-roughening process can be applied on the bottom-left and the bottom-right corners of the light-exiting surface of the light-guide plate 10 so that the luminance on the bottom-left and on the bottom-right corners of the light-guide plate 10 is increased. However, the method of increasing local luminance by burnish is unidirectional burnish. That is to say, the cutting tools have to burnish from left to right, which will make the direction of the light in the light-guide plate 10 be oblique towards right, increasing the luminance of the bottom-right corner while decreasing relatively even more the luminance of the bottom-left. Alternatively, burnish can be done from right to left, which will make the direction of the light in the light-guide plate 10 be oblique towards left, increasing the luminance of the bottom-left corner while decreasing relatively even more the luminance of the bottom-right.
If burnish is done on the light-entering surface of the light-guide plate 10 from left to right first and then from right to left, the luminance on the bottom-left and the bottom-right corners of the light-guide plate 10 does not increase remarkably. In other words, by using the cutting tools to make the surface microstructure of the light-entering surface asymmetric, the light entering the light-guide plate will scatter unidirectionally.
Accordingly, the present invention provides a backlight structure, which can increase the luminance on the bottom-left and on the bottom-right corners of the light-guide plate. Thereby, the problem described above can be solved.